@import url("https://fonts.googleapis.com/css2?family=Montserrat:wght@500&display=swap");
:root {
    --y: 50%;
    --blur: 0.5vmax;
    --focus-range: 1vh;
    --blur-range: 25vh;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html,
body {
    background-color: black;
    overscroll-behavior-x: none;
    overscroll-behavior-y: none;
    overflow: hidden;
    /*
  cursor: none;
  */
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
    user-select: none;
}

.box-bg {
    width: 100vw;
    height: 100vh;
    font-family: "Montserrat", serif;
    text-align: center;
    line-height: 1;
    display: flex;
    justify-content: center;
    align-items: center;
}

main {
    z-index: 1;
}

h1 {
    font-size: 5vw;
    color: #fff;
}

#bg,
#bg_mask {
    /* ãµã¡ãƒœã‚±å¯¾ç­– */
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    margin: calc(var(--blur) * -1);
    background: url(https://images.unsplash.com/photo-1622664843830-e79e37074452?crop=entropy&cs=srgb&fm=jpg&ixid=M3wzMjM4NDZ8MHwxfHJhbmRvbXx8fHx8fHx8fDE2OTg5NTQzMTR8&ixlib=rb-4.0.3&q=85) no-repeat center bottom/cover;
}

#bg {
    filter: blur(var(--blur));
}

#bg_mask {
    -webkit-mask-image: linear-gradient( transparent, transparent calc(var(--y) - var(--focus-range) - var(--blur-range)), black calc(var(--y) - var(--focus-range)), black var(--y), black calc(var(--y) + var(--focus-range)), transparent calc(var(--y) + var(--focus-range) + var(--blur-range)), transparent);
    mask-image: linear-gradient( transparent, transparent calc(var(--y) - var(--focus-range) - var(--blur-range)), black calc(var(--y) - var(--focus-range)), black var(--y), black calc(var(--y) + var(--focus-range)), transparent calc(var(--y) + var(--focus-range) + var(--blur-range)), transparent);
}